Compressor

ABSTRACT

A rotary vane compressor having a rotor eccentrically received in a cylindrical chamber. The rotor has radially movable vanes thereon, the outer peripheries of which carry shoes contacting the inner diameter of the cylinder wall. At the point of tangency between the rotor and inner diameter wall of the chamber, a groove is provided in the wall. A port extends from the bottom wall of the groove to the high-pressure exit and a rectilinear tangency seal is received in the groove.

United States Patent King et al. [4 1 Mar. 28, 1972 s41 COMPRESSOR FOREIGN PATENTS 0R APPLICATIONS [72] Inventors: David G. King, Chesterland; William P. 26,252 3/1953 Finland ..418/l25 Burke, Jr., Wickliffe, both of Ohio 687,630 2/ 1953 Great Britain ..418/l25 [73] AssIgnee: TRW Inc., Cleveland, 01110 Primary Examiner carlton R Cmyle [22] Filed: June 22, 1970 Attorney-Hill, Sherman, Meroni, Gross & Simpson [21] Appl. No.: 47,993 [57] ABSTRACT A rotary vane compressor having a rotor eccentrically E ((51 8/3 received in a cylindrical chamben The rotor has radially [58] i i 125 128 movable vanes thereon, the outer peripheries of which carry shoes contacting the inner diameter of the cylinder wall. At the point of tangency between the rotor and inner diameter [56] References Cited wall of the chamber, a groove is provided in the wall. A port UNITED STATES PATENTS extends from the bottom wall of the groove to the high-pressure exit and a rectilinear tangency seal is received in the 3,539,281 11/1970 Kramer ....418/l25 groova 1,385,880 7/1921 Master ....418/129 3,123,01 l 3/1964 Wood ..4l8/125 12 Claims, 15 Drawing Figures PATENTEDHAR28 I972 3,652,191

sum 1 or 4 I N VEN'TORS COMPRESSOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to compressors and motors and more particularly to a tangency seal for a rotary vane compressor.

2. Prior Art Rotary vane compressors of the type to which this invention applies are known to the art. (See for example patent to Kilgore, U.S. Pat. No. 3,385,513) Such compressors are widely adapted for use in cooling systems for compressing the refrigerant vapor. These devices are highly effective as automobile air conditioner compressors.

The compressor consists of an outer cup-shaped casing closed at one end by an end plate. A cylinder having a smaller outer diameter than the inner diameter of the casing is received in the casing between the end plate and an internally disposed end plate. The internal bore of the cylinder is used as the compressor chamber. The cylinder is coaxially aligned with the casing. An eccentrically positioned rotor is supported in the cylinder bore by the two end plates. A plurality of radially extending, radially movable vanes extend from the rotor into contact with the inner diameter of the cylinder. Due to.

the eccentric positioning of the rotor within the cylinder, the area between the rotor vanes changes as the rotor rotates. The vanes contact the end plates and extend axially the length of the cylinder thereby providing sealed changeable volume areas between individual vanes and the end plates. One of the end plates has an inlet associated therewith and spaced such that it is open to the area between the vanes when that area is large prior to compressing, and is thereafter closed. As the rotor rotates, fluid entrapped in the chambers between the vanes will be compressed as the rotor approaches the point of tangency. The point of tangency is the point where the outer diameter of the rotor contacts or is closest to the inner diameter of the cylinder wall. This is a constant point and as the various areas between the vanes are circumferentially revolved into position adjacent this point, the fluids in these areas will reach their highest state of compression. A valved outlet port is positioned adjacent the point of tangency on the high pressure side.

Placement of the outlet port is important. If the outlet port is extremely small and placed immediately at the point of tangency, the compression will be extremely high and the power necessary to drive the compressor may be exhorbitant. For this reason, the exit port is normally spaced adjacent the point of tangency and is sufficiently large to exhaust the space between the vanes at the desired compression pressure during full-speed operation of the device. Valving the exhaust port allows control of the exhaust pressure by allowing the exhaust port to open at a given pressure irrespective of speed of operation of the device.

The radially outer ends of the vanes may be equipped with shoes for riding against the inner diameter of the cylinder. As the vanes pass the outlet, they may still travel a distance before reaching the point of tangency. Fluids, including lubricating fluids, entrapped between the exhaust port and the point of tangency, can cause compression of the vane into the rotor vane slot. This will cause a breaking of the seal between the high pressure side and the low pressure side of the compressor as the vane passes the point of tangency. Further chatter may be created by the lifting of the shoe off of the inner diameter of the cylinder and the resumption of contact between the shoe and cylinder as the vane passes the point of tangency. The pressures built up by entrapped lubricating fluids and compressed fluids at the point of tangency can be extreme, and can result in system inefficiencies and excessive wear. If the vane is pressed into the vane slot a sufficient distance, it is possible for a free riding shoe to lose contact with the vane.

This problem has not heretofore been effectively solved by the prior art compressors. It has been suggested (see for example U.S. Pat. No. 569,350 to Potter) to provide pressure backed seal members at the point of tangency. However, when compressor generated pressure is entrapped interiorly of the cylinder behind a seal member, the seal member will be forced against the rotor with a pressure which may be excessive, thereby causing undue wear on both the rotor and seal member.

SUMMARY It is a primary object of this invention to provide a solution to the above-described problem through the provision of a tangency seal.

The compressor of this invention is substantially the same as prior art compressors in many respects but incorporates, in addition with other new features, a tangency seal. In a preferred embodiment, the tangency seal comprises a rectilinear groove in the inner diameter face of the cylinder at the point of tangency. The groove extends the axial length of the cylinder from end cap to end cap. A rectilinear seal member is received in the groove. An escape path is provided from the high pressure side of the seal to the bottom wall of the groove. In this manner, pressure fluids entering the groove between the seal member and the groove wall will act between the back of the seal member and the bottom of the groove to force the seal member into contact with the rotor and vanes at the point of tangency thereby maintaining the tangency seal. Valved exhaust ducts extend from the bottom wall of the groove to the exterior of the cylinder where they communicate with the high pressure exhaust area. This provides for an escape of excess pressure from the seal groove.

It is therefore an object of this invention to provide an improved rotary vane compressor. 7

It is a further object of this invention to provide a rotary vane compressor'with a seal at the point of tangency between the rotor and chamber wall.

It is a further and more specific object of this invention to provide a rotary vane compressor having a rectilinear tangency seal received in a groove at the point of tangency between the rotor and the wall of the rotor receiving cylinder. V

It is yet another and more specific object of this invention to provide a tangency seal for a rotary vane compressor wherein the seal is a rectilinear groove receiving a rectilinear strip which is pressure-backed into contact with the outer diameter of the rotor and which bleeds excess pressure to the exterior of the compression chamber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional plan view of the compressor of this invention taken along the lines II of FIG. 12.

FIG. 2 is a transverse cross-sectional view of the compressor taken along the lines IIII of FIG. 1.

FIG. 3 is a fragmentary plan view taken along the lines III- III of FIG. 2.

FIG. 4 is a fragmentary plan view taken along the lines IV- IV of FIG. 2, illustrating the tangency seal porting.

FIG. 5 is a cross-sectional view of the seal of FIG. 4.

FIG. 6 is a view of the pressure porting taken along the lines VI-VI of FIG. 2.

FIG. 7 is a cross-sectional view taken along the lines VII- VII of FIG. 6.

FIG. 8 is atop plan view of the rectilinear tangency seal of this invention.

FIG. 9 is a fragmentary cross-sectional view of the seal of F IG. 8 in position in the seal groove.

FIG. 10 is a view similar to FIG. 9 with the section taken at a different point.

FIG. 11 is a cross-sectional view of one end plate of the compressor taken along the lines XI-XI of FIG. 1.

FIG. 12 is an end plan view of the compressor of this assembly.

FIG. 13 is a cross-sectional view of the compressor taken along the lines XIII-XIII of FIG. 12, illustrating the compressor lubricating port. I

FIG. 14 is a cross-sectional view of another embodiment of the tangency seal of this invention.

FIG. is a top plan view of the tangency seal modification of FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a longitudinal cross-sectional view of the compressor of this invention. The compressor includes a pressureretaining housing 21 which is cup-shaped and closed at the open end by an end plate 22 attached thereto by a plurality of circumferentially spaced fastening nuts and bolts 23. An internal end plate 24 is positioned within the housing 21 in spaced relation to the bottom 25 thereof. The end plate 24 is attached to the end plate 22 by a plurality of circumferentially spaced bolts 26. The end plates 22 and 24 are spaced from one another axially and are of a diameter equal to the internal diameter of the housing 21 so as to seal the space between the plates. Entrapped between the plates 22 and 24 is a compressor cylinder 28 which has an outer diameter 29 less than the inner diameter 30 of the cup-shaped housing 21, thereby providing a circumferential space 31 between the outer diameter 29 of the cylinder 28 and the inner diameter 30 of the housing.

The inner diameter 32 of the cylinder 28 defines the radially outer limits of the compressor chamber 33 formed between the end caps 22 and 24. The cylinder 28 is concentric within the housing and is held in place entrapped between the end caps 22 and 24. Y

A rotatable shaft 35 is received through the end plate 22 with respect to the housing 21 and the cylinder 28. An eccentrically positioned recess 36 in the end cap 24 receives an antifriction bearing 37 which supports the inner end 38 of the shaft 35.

;A correspondingly positioned recess 39 in the outer face of the end plate 22 receives an anti-friction bearing 40 which supports the other side of the shaft 35. A closure plate 41 is bolted onto the outside face of the end plate 22 to close the recess 39. The closure plate 41 carries a shaft seal 42 which seals the recess 39 from the ambient atmosphere and bottoms against a shaft-carried radially extending abutment 43. v

The shaft 35 has its end 46 projecting from the compressor 20 where it may be driven by an outside power source.

A rotor disk 47 is journalled onto the shaft 35 in the space between the end plates 22 and 24. The rotor 47 is a circular disk having a radius equal to the shortest distance between the shaft center and the inner diameter wall 32 of the pump chamber cylinder 28. Therefore, due to the eccentric mounting' of the shaft within the cylinder, the rotor contacts the cylinder wall at the point where the distance between the shaft center and the inner diameter wall 32 of the cylinder is the smallest. This is known as the point of tangency 50.

As best illustrated'in FIG. 2, the rotor 47 has a plurality of blind slots extending thereinto equidistantly circumferentially spaced. The slots 51 extend the length of the rotor 47 and terminate at a point 52 spaced from the centerpoint of the rotor. Vanes 53 are slidably received in the slot 51 having their outer ends 54 contoured to receive shoes 55. The shoes may be freely received on the ends of the vanes or may be attached thereto. The outer face of the shoes 56 rides against the inner diameter 32 of the cylinder wall in sealing engagement therewith.

The slots 51 are illustrated as being four in number and are positioned equidistantly around the rotor diametrically opposed to one another. Bores 60 project through the rotor 47 and shaft 35 from the bottoms 52 of diametrically opposed slots 51. Pins 61 are received in the bores 60 and in blind bores 62 in the bottoms of the opposed vanes 53. The pins 61 are surrounded by coil springs 63 which cooperate with the pins to move the opposed vanes as a unit so that when one vane is forced into its respective slot a given distance, the diametrically opposed vane is forced out of its respective slot an equal amount. In this manner, due to the eccentric positioning of the rotor within the cylinder, opposed vanes will ride against the cylinder wall at diametrically opposed posiinto the housing 21. The shaft 35 is positioned eccentrically tions. In order to provide for non-intersection of the bores 60, the bores for non-diametrically opposed sets of slots 51 are offset from one another, as is best illustrated in FIG. 1.

It can therefore be seen that the vanes 53 divide the area within the cylinder 28 not filled by the rotor 47 into four quadrants. As the rotor rotates, the quadrant positions are changed as is their volume. The quadrants are defined as the area between adjacent vanes and between the outer diameter of the rotor and the inner diameter of the cylinder wall. The space between the rotor and the cylinder wall changes from the point of tangency where it approaches zero to the position diametrically opposed to that point where it is the greatest.

sides of the cylinder, the low-pressure side being downstream in the direction of rotation of the rotor from the pointof tangency and the highpressure side being upstream from the point of tangency. Placing an inlet on the low-pressure side and an outlet on the high-pressure side provides a compressor pump.

As best illustrated in FIG. 2, the cylinder 28 is provided-with two flat land bosses 60 and 61 on the outer diameter of the cylinder. The bosses are positioned on the high-pressure side of the cylinder,'and are circumferentially spaced from one another. The boss.60 has a bore 62 therethrough which is circumferentially spaced a short distance-downstream from the point of tangency 50. The bore 62 provides a high-pressure outlet to the exterior of the cylinder 28 As can be seen from FIG. 3, preferably three bores are provided: 62a, 62b, and 624, in axial alignment with one another. The bores are closed by a three-fingered reed valve 64. The ends of the fingers 64a, 64b and 640 overlie the outlet ports 62 while the connecting portion'64d of the reed valve is attached to the boss 60, thereby providing a cantilever holddown. A travel limiter 66 prevents unrestricted opening of the fingers of the reed valve to provide for quick closing. A scavenge slot 67 reduces pressure under the valve fingers to promote closing. Therefore, when the pressure in the quadrant communicating with the ports 62 is greater than the pressure exterior of the cylinder by an amount sufficient to overcome the reed valve, the ports will open, communicating the interior of the cylinder with the exterior.

When the trailing vane of the quadrant passes the port 62, the pressure interior of the cylinder at the point of the ports will drop to the pressure of the following quadrant. When this pressure is less than the pressure exterior of the ports, the reed valve 64 will close, preventing a backflow of pressure into the compressor section interior of the cylinder.

The boss 61 has a plurality of bores 65 therethrough which are open to the interior of the cylinder on the high pressure side at a point remotely spaced from the tangency point 50. The ports 65 are closed by a reed valve 660 and function as scavenging ports during startup. When the compressor is turned off, a large amount of lubricating and refrigerant fluid can build up in the low pressure side of the compressor. During this period of time, there is little or no pressure retained in the housing 21 exterior of the cylinder so that the exterior pressure acting against the reed valve 66a is small. Attempting to compress the fluid in the compressor at the time of startup can place a heavy power load on the compressor driver. During such situations, the reed valve 660 will open, allowing evacuation of the interior of the cylinder at a lower pressure than would be present adjacent the outlet 62. This allows the compressor to initially operate without fully compressing the lubricating and refrigerant fluid which accumulates during shutdown. Thus, the compressor will achieve operating speed without extreme startup loads. During normal operation, the pressure exterior of the reed valve 66a will be greater than the pressure in the quadrant open to the ports 65, thereby maintaining the valve in a closed position.

As best illustrated in FIGS. 1 and 2, it can be seen that the ports 62 and 65 communicate the interior of the cylinder 28 to the interior of the housing 21 in the peripheral space 31 radially outwardly from the outer diameter of the cylinder. This area is blocked at the one end of the housing by the end plate 22 which has circumferential seals 70 associated therewith. The pressure is thereby maintained within the housing 21.

The internal end plate 24 has axial ports 71 associated therewith, which pass the pressure fluid through the end plate from the space 31. A blockage member 72 divides the area 31 from a chamber 73 at the bottom of the cup-shaped housing. A demister device 74 is interposed between the chambers 31 and 73 and is retained in place between the internal end plate 24 and the member 72.

During operation of the compressor, a slight pressure differential exists between the area 31 and the area 73. This pressure differential forces the mixture of superative refrigerant and lubricant suspended in particle form from the chamber 31 through the opening 71 into the annular area 75 surrounding the demister 74. The, refrigerant andlubricant then passes through the demister into the area 73. The demister consists of a suitably porous material which has the property of causing fine particles of lubricant dispersed in refrigerant to collect and exit in droplet form. The lubricant droplets are sufficiently heavy to fall out of the refrigerant stream and drop to the bottom of the area 73 where they collect in a lubricant reservoir. This reduces the amount of lubricant which is circulated through the air conditioner system. A valve outlet 78 communicates to the area 73 providing the final outlet from the compressor.

A valved inlet 79 is also provided on the compressor. The inlet is in communication with a bore 80 (best illustrated in FIG. 11) in the end plate 22. The bore 80 is positioned to the side of the end plate 22 corresponding to the low pressure side of the compression chamber. The bore 80 communicates with a kidney-shaped opening 81 open to the interior of the cylinder on the low-pressure side. A one-way check valve 82 is associated with the inlet 79 to prevent backflow of pressured fluid from the compressor cylinder through the kidney opening 81 and out of the compressor. This allows for shutdown of the compressor with a minimum of reverse rotation of the rotor.

Lubrication of the anti-friction bearing unit 40 is provided by a lubrication duct 85 which extends from the space 39 through the end plate 22 where it communicates with a duct 86 through the cylinder 28. The duct 86 communicates to a duct 87 which terminates in the lubricant reservoir at the bottom of the space 73. In the preferred embodiment illustrated, the compressor is designed to be operatively positioned with the intake 79 projecting laterally from the bottom regions of the air compressor. Therefore, the ducting 85, 86 and 87 is positioned adjacent that portion of the compressor. In other embodiments where the compressor is designed to be assembled with a different portion at the bottom, the ducting will be circumferentially spaced from the illustrated position so that the duct 87 always opens to the bottom portion of the space 73. Because of the pressure difierential between the area 73 and the area 39, lubricant will be forced through the ducting 87, 86 and 85 into the area 39 where it will serve to lubricate the bearing assembly 40. Some of this lubricant will also extend into the slots 51 and therethrough to lubricate the bearing assembly 37 as well as lubricating the slots and vanes reciprocatively mounted therein. Further, a portion of the lubricant will be present in the refrigerant stream and will serve to lubricate the interior of the compression chamber while other portions of the lubricant supply will act to lubricate the contact area between the rotor and end plates.

As a vane 53 approaches the outlet port 62, the fluid remaining in the quadrant immediately ahead of the vane reaches its greatest state of compression. After the vane shoe passes the port 62, a small amount of fluid and lubricant will remain in the quadrant ahead of the shoe. Extreme pressures develop as the shoe approaches the point of tangency. Heretofore, this pressure has normally been relieved by forcing the vane into its corresponding slot. This has caused the shoe to lift off the face of the cylinder wall until the shoe has passed the point of tangency. Thereafter, the shoe will return to the cylinder wall in the absence of the counter pressure as the shoe enters'the low pressure side of the cylinder. This has resulted in vane clatter due to the inward displacement of the vane and shoe and return to contact with the cylinder wall. Attempting to relieve this by retaining a slight spacing between the rotor and the cylinder wall at the closest point decreases the efi'ectiveness of the compressor while allowing considerable erosion of the cylinder wall due to high-pressure fluid bleed.

Our invention provides a seal at the tangency line which maintains contact between the rotor, shoes, and cylinder while at the same time allowing an escape path for trapped fluid.

The seal consists of a rectilinear groove in the inner diameter wall of the cylinder. The groove 100 extends from the end plate 22 to the end plate 24. Bleed ports 101 extend I from the bottom wall 102 to the outside of the cylinder. The rectilinear groove 100 is positioned at the line of tangency of the rotor 47 and cylinder 28.

As illustrated in FIG. 5, the bleed ports 101 are preferably two in number and are positioned adjacent either end of the groove 100. The ports 101 are closed by a double reed valve 103 attached to the exterior of the'cylinder as by a screw 104. A pin 105 prevents rotation of the reed valve 103. Provision of the bleed ports 101 allows escape of pressure from the groove 100. This monitors the amount of force exerted against the seal member. Dimensioning of the ports 101 with respect to the dimensions of the outlet and dimensioning of the flow passages into the groove and resistance of the valve 103 allows maintenance of desired pressure levels in the groove while bleeding excess pressures. It is a feature of this invention that excess pressures are bled to the same area as the compressed fluid from the outlet. Thus, there is no loss of compressor efficiency as would be the case if the bleed ports 101 exited exterior of the system.

A rectilinear seal member 106 is received in the groove 100 and functions as the seal contact member.

The seal member 106 is dimensioned to substantially fill the groove 100. The outer face 108 of the seal member 106 bottoms against the back wall 102 of the groove 100 while the trailing face 109 and leading face 110 of the member 106 are in contact with the trailing wall 111 and leading wall 112 of the groove 100. The inner face 113 of the member 106 is preferably inclined slightly upwardly from the leading face 110 to the trailing face 109. The depth of the member 106 is dimensioned such that the leading face edge 114 lies slightly below the inner diameter of the cylinder 28 while the trailing edge 115 lies slightly above the inner diameter. In this manner, as the shoe 55 of any given vane rides over the seal, it will not encounter an abutment caused by the leading edge 1 14 of the seal member or by the edge at the intersection of the trailing wall 111 of the groove and the inner diameter of the cylinder. The dimensions are maintained small so as to prevent clatter which might otherwise be caused by the shoe falling into the groove or falling off of the seal member. By maintaining the height dimensions small with respect to the face of the shoe, a

smooth transition will be effectuated.

In order for the compressor to work at its optimum efficiency, it is necessary to maintain an effective seal at the line of tangency between high-pressure and low-pressure sides. Normally, during operation, it is difficult to maintain such a seal. Our invention provides a pressure backing for the seal member 106 which will maintain it in riding contact with the outer diameter of the rotor 47. In the preferred embodiment illustrated in FIGS. 8, 9 and 10, the seal member 106 has a plurality of relieved areas or grooves in the leading face 110. These grooves communicate with relieved areas or grooves 121 in the outer face of the seal member 106. Therefore, the grooves 120 are open to the interior of the cylinder on the high-pressure side of the seal so that pressure contained in the cylinder between the port 62 and the seal member 106 will be communicated to the bottom of the groove 100 in the area of the grooves 121 where it will act between the bottom wall 108 of the groove 100 and the bottom of the grooves 121 to force the seal member 106 against the rotor 47, thereby maintaining contact between the seal member 106 and them- 101'.

As the trailing shoe of any given quadrant passes the port 62 and approaches the sealed tangency line, fluid trapped ahead of the shoe is highly compressed. In the preferred embodiment, some of the grooves 121 communicate the groove 100 to the exterior of the cylinder through the reed valve 103. This provides an escape path for trapped fluids which, when their pressure is greater than the pressure contained in the area 31 surrounding the cylinder, -will overcome the reed valve 103 and flow through the openings 101. In one embodiment a plurality of longitudinal grooves 125 may be formed in the outer face 108 of the seal member 106 communicating each of the grooves 121. In this manner, fluid in all of the grooves will be communicated to the ports 10]. Alternatively, as illustrated in FIG. 8 and the cross-sectional view of FIG. 10, which is taken between the areas of the grooves 120 and 121, the seal member 106 may substantially fill the groove 100.

' FIGS. 14 and 15 illustrate another embodiment of the seal member. In this embodiment, the seal strip 130 has a plurality of raised beads 13] on the outer face 132. The beads bottom against the back wall 108 of the groove 100. This provides a larger space between the outer face 132 and the back wall of the groove in which the pressure of trapped fluids may act.

Provision of the tangency seal maintains a point of tangency between the rotor and cylinder at the seal even though thermal expansion of the elements may otherwise create a gap. Due to the provision of the bleed holes 101, the tangency contact is maintained without excessive force between the seal member and the rotor which might otherwise result in placing a heavier load on the compressor driver and which would contribute greatly to parts wear.

It can therefore be seen from the above that our invention provides for an improved rotary vane compressor which has a seal means at the line of tangency between the vane carrying rotor and the inner wall of the compressor cylinder. The seal is pressure-responsive, and in the preferred embodiment, includes a rectilinear seal member received in a groove in the cylinder wall, the seal member having relieved areas allowing pressure to flow behind the seal member in the groove thereby biasing the seal member against the rotor. Ports communicate the bottom of the groove to the exterior of the cylinder to an area in the pressure flow thereby providing an escape path for fluids trapped between the exhaust port of the cylinder and the line oftangency.

Although the teachings of our invention have herein been discussed with reference to specific theories and embodiments, it is to be understood that these are by way of illustration only and that others may wish to utilize our invention in different designs or applications.

We claim as our invention:

1. In a rotary vane compressor having a vane carrying rotor eccentrically received in a pressure cylinder, the improvement of a seal member at the line of tangency between the rotor and cylinder, said seal member pressure backed whereby it is biased towards the rotor, and means venting pressure from the back of the seal member to the exterior of the pressure cylinder.

2. The improvement of claim 1 wherein the seal member is a rectilinear strip received in a groove in the cylinder wall at the line of tangency, the said strip having passageways associated therewith providing communication between the high-pressure side of the compressor and areas between the strip and the bottom of the groove whereby the strip will be pressurebacked to bias it towards the said rotor.

3. The improvement of claim 2 wherein the venting means are passageways communicating the said groove to the exterior of the said cylinder.

4. A compressor comprising: a cup-shaped housing, a first end plate closing said housing, a cylinder contained in said housing having an outer diameter less than the inner diameter of said housing, one end of said cylinder closed by said first end plate, the other end of said cylinder closed by a second end plate, said second end plate positioned within said housing spaced from the bottom thereof, a rotor supported by said end plates, said rotor eccentrically positioned within said housing having a diameter sufi'icient to tangentially contact the inner diameter of said cylinder along a line at one point of the cylinders circumference, a plurality of slidable radial vane assemblies received in slots in said rotor, said vane assemblies dimensioned to contact the inner diameter of said cylinder, said rotor and vane assemblies rotatable within said cylinder, a groove in the said inner diameter of said cylinder between the said end plates at the line of tangency, an elongatedseal member received in said groove having an interface contacting the said rotor along said line of tangency effective to divide said cylinder into high-pressure and low-pressure sides around its circumference, an outlet from said cylinder spaced from said line of tangency on the high-pressure side thereof, an inlet to said cylinderfrom the exterior of the housing communicat I ing with the interior of the said cylinder on the low-pressure side of said line of tangency, first means utilizingpressure developed interior of said cylinder for biasing the said seal member towards the said rotor, and second means venting the pressure from the groove to the exterior of the cylinder.

5. The compressor of claim 4 wherein the said first means comprises passageway means communicating the bottom of saidlgroove with the high-pressure side of said cylinder whereby compressed fluids in the said high-pressure side of v said cylinder are communicated with an area between the bottom of said groove and the said seal means to bias the said seal means away from the bottom of the said groove.

6. The compressor of claim 5 wherein the said second means includes passage means communicating the bottom of the said groove with the exterior of the cylinder and wherein compressed fluid passing from the said cylinder through the said passage means is co-mingled with compressed fluid from the said exit port on the said high-pressure side of the said compressor.

7. The compressor of claim 6 wherein the said passage means from the said groove to the exterior of the said cylinder is blockable by a one-way valve preventing backflow from the exterior of the cylinder to the said groove.

8. A tangency seal for rotary vane compressors which have eccentric rotors received within a cylinder between end plates and wherein the rotor is normally tangent to the inner diameter of the cylinder along a line comprising: a groove in the inner wall of said cylinder along said line of tangency, an elongated seal member strip received in said groove and means utilizing pressure developed by said compressor for biasing the said strip away from the bottom of said groove towards the said rotor, the said means including spaces between the said bottom of said groove and an opposed face of the said strip and additional passage means between the said spaces and the high-pressure side of the said compressor thereof and porting means porting the spaces to the exterior of the cylinder.

9. A tangency seal for rotary vane compressors having a rotor eccentrically positioned within a closed-ended cylinder, the rotor having inwardly and outwardly slidable members the ends of which contact the cylinder wall and the rotor normally tangent to the cylinder wall along a line of tangency, the line of tangency dividing the cylinder into highand low-pressure areas, comprising: a relieved area in said cylinder wall along said line, a seal member in said relieved area, said seal member movable in said relieved area, means spacing portions of said seal member from the bottom of said relieved area, passage means communicating the high pressure area with the portions of the bottom of said relieved area and the said portions of said seal member to bias the seal member away from the bottom in dependent response to the presence of pressured fluids between the said seal member and said bottom of said relieved area, and second passage means communicating the outside of the cylinder with the said relieved area to provide an exit path from said cylinder for said pressured fluids in the said relieved area and one-way valving associated with said second passage means preventing backflow into the said relieved area.

10. The seal of claim 9 wherein the said relieved area is a rectilinear groove in the cylinder wall extending the length of the line of tangency and circumferentially to either side thereof a short distance and the said seal member is a substantially rectilinear strip received in the said groove having a leading face contacting the high-pressure side wall of said groove and a trailing face contacting the low-pressure side wall of the said groove with an outer face bottomed against the bottom of the said groove, the said passage means comprising grooves in the said leading face.

11. The seal of claim 10 wherein the said portions of the said seal member comprise grooves in the outer face of the said seal member.

12. The tangency seal of claim 10 wherein the said leading face has a depth less than the depth of said groove wherein said leading face normally tenninates within the said groove and the said trailing face hasa depth greater than the depth of the groove wherein said trailing face normally projects radially inwardly of said groove.

I 1.! I l 

1. In a rotary vane compressor having a vane carrying rotor eccentrically received in a pressure cylinder, the improvement of a seal member at the line of tangency between the rotor and cylinder, said seal member pressure backed whereby it is biased towards the rotor, and means venting pressure from the back of the seal member to the exterior of the pressure cylinder.
 2. The improvement of claim 1 wherein the seal member is a rectilinear strip received in a groove in the cylinder wall at the line of tangency, the said strip having passageways associated therewith providing communication between the high-pressure side of the compressor and areas between the strip and the bottom of the groove whereby the strip will be pressure-backed to bias it towards the said rotor.
 3. The improvement of claim 2 wherein the venting means are passageways communicating the said groove to the exterior of the said cylinder.
 4. A compressor comprising: a cup-shaped housing, a first end plate closing said housing, a cylinder contained in said housing having an outer diameter less than the inner diameter of said housing, one end of said cylinder closed by said first end plate, the other end of said cylinder closed by a second end plate, said second end plate positioned within said housing spaced from the bottom thereof, a rotor supported by said end plates, said rotor eccentrically positioned within said housing having a diameter sufficient to tangentially contact the inner diameter of said cylinder along a line at one point of the cylinder''s circumference, a plurality of slidable radial vane assemblies received in slots in said rotor, said vane assemblies dimensioned to contact the inner diameter of said cylinder, said rotor and vane assemblies rotatable within said cylinder, a groove in the said inner diameter of said cylinder between the said end plates at the line of tangency, an elongated seal member received in said groove having an interface contacting the said rotor along said line of tangency effective to divide said cylinder into high-pressure and low-pressure sides around its circumference, an outlet from said cylinder spaced from said line of tangency on the high-pressure side thereof, an inlet to said cylinder from the exterior of the housing communicating with the interior of the said cylinder on the low-pressure side of said line of tangency, first means utilizing pressure developed interior of said cylinder for biasing the said seal member towards the said rotor, and second meanS venting the pressure from the groove to the exterior of the cylinder.
 5. The compressor of claim 4 wherein the said first means comprises passageway means communicating the bottom of said groove with the high-pressure side of said cylinder whereby compressed fluids in the said high-pressure side of said cylinder are communicated with an area between the bottom of said groove and the said seal means to bias the said seal means away from the bottom of the said groove.
 6. The compressor of claim 5 wherein the said second means includes passage means communicating the bottom of the said groove with the exterior of the cylinder and wherein compressed fluid passing from the said cylinder through the said passage means is co-mingled with compressed fluid from the said exit port on the said high-pressure side of the said compressor.
 7. The compressor of claim 6 wherein the said passage means from the said groove to the exterior of the said cylinder is blockable by a one-way valve preventing backflow from the exterior of the cylinder to the said groove.
 8. A tangency seal for rotary vane compressors which have eccentric rotors received within a cylinder between end plates and wherein the rotor is normally tangent to the inner diameter of the cylinder along a line comprising: a groove in the inner wall of said cylinder along said line of tangency, an elongated seal member strip received in said groove and means utilizing pressure developed by said compressor for biasing the said strip away from the bottom of said groove towards the said rotor, the said means including spaces between the said bottom of said groove and an opposed face of the said strip and additional passage means between the said spaces and the high-pressure side of the said compressor thereof and porting means porting the spaces to the exterior of the cylinder.
 9. A tangency seal for rotary vane compressors having a rotor eccentrically positioned within a closed-ended cylinder, the rotor having inwardly and outwardly slidable members the ends of which contact the cylinder wall and the rotor normally tangent to the cylinder wall along a line of tangency, the line of tangency dividing the cylinder into high- and low-pressure areas, comprising: a relieved area in said cylinder wall along said line, a seal member in said relieved area, said seal member movable in said relieved area, means spacing portions of said seal member from the bottom of said relieved area, passage means communicating the high pressure area with the portions of the bottom of said relieved area and the said portions of said seal member to bias the seal member away from the bottom in dependent response to the presence of pressured fluids between the said seal member and said bottom of said relieved area, and second passage means communicating the outside of the cylinder with the said relieved area to provide an exit path from said cylinder for said pressured fluids in the said relieved area and one-way valving associated with said second passage means preventing backflow into the said relieved area.
 10. The seal of claim 9 wherein the said relieved area is a rectilinear groove in the cylinder wall extending the length of the line of tangency and circumferentially to either side thereof a short distance and the said seal member is a substantially rectilinear strip received in the said groove having a leading face contacting the high-pressure side wall of the said groove and a trailing face contacting the low-pressure side wall of the said groove with an outer face bottomed against the bottom of the said groove, the said passage means comprising grooves in the said leading face.
 11. The seal of claim 10 wherein the said portions of the said seal member comprise grooves in the outer face of the said seal member.
 12. The tangency seal of claim 10 wherein the said leading face has a depth less than the depth of said groove wherein said leading face normally terminates within the said groove and the said trailing face has a depth gReater than the depth of the groove wherein said trailing face normally projects radially inwardly of said groove. 